Apparatus for simultaneously polishing both faces of a travelling strip of glass



i 29, 1947. F. B. WALDRON ETAL 2,419,925

APPARATUS FOR SIMULTANEOUSLY POLISHING BOTH FACES OF A TRAVELLING STRIP OF GLASS Filed April 9, 1946 s Sheets-sheaf 1 lnvenimg Attorneys April 29, 194 7.

F. B. WALDRON- ET AL 9,9 5 APPARATUS FOR SIMULTANEOUSLY POLISHING BOTH FACES OF A TRAVELLING STRIP OF GLASS Filed April 9, 1946' 3 Sheets-Sheet 2 F IG. 6.

Attorneys Patenteol Apr. 29, 1947 APPARATUS FOR SIMULTANEOUSLY POL- ISHING BOTH FAQES OF A TRAVELLING STRL OF GLASS Frederic Barnes Waldron, Prescot, and James Harris Griffin, St. Helens, England, assignors to Pilkington Brothers Limited, Liverpool,

England, a British company Application April 9, 1946, Serial No. 660,742 In Great Britain September 13, 1944 5 Claims.

This invention relates to apparatus for simultaneously polishing both faces of a travelling strip of glass.

Such form of apparatus commonly comprises polishing tools adapted to operate on the underface of the glass strip, whilst at the same time they serve to support the strip, each such tool including a plurality of polishing pads each adapted to turn on a substantially vertical axis, the tool being mounted on a frame which is adapted to turn so as to bring each pad to an edge of the glass.

The tool may either be supported on a single frame with central driven shaft or may be supported on a plurality of sub-frames in turn supported on a main frame with central driven shaft, each sub-frame (if used) being free to rotate on its support on the main frame. Each tool is provided with means of vertical adjustment, whereby the strip of glass supported by the plurality of tools can be kept free of bends in passing through the apparatus.

Polishing is effected by the rubbing of the pads over the glass, while rouge and water is supplied either to the pads or to the glass. After a certain time of operation, rouge becomes caked on the pads to form a hard layer, in which foreign matter such as glass splinters may be embedded, and the polishing action is then impaired. The pads then have to be cleaned by removing the hard layer and, to effect this, access must be obtained to the operative surface of the pads. Further, the pad coverings gradually wear and may become damaged and then the covering must be removed and replaced.

If a polishing tool operating on the under surface of a strip of glass be lowered so as to give access to the surfaces of the pads, there is considerable risk of the travelling glass, which is then left unsupported over the tool, bending and then breaking. Also, when one or some of the pads have their covering replaced, the pads with new coverings are not accurately in the same plane as the remaining pads with partially worn cover ings. This has the result of imposing bending stresses on the glass which may be sumcient to break the glass.

A main object of the present invention is to provide in apparatus for simultaneously polishing both faces of a travelling strip of glass, means whereby a pad operating on the underface of the glass can be rapidly moved away so that the pad can either be replaced or its surface scraped or cleaned, and its surface adjusted into the plane 2 in which the other pads mutually support the glass.

In accordance with the present invention apparatus for polishing the under surface of a horizontal travelling strip of glass comprises a rotatable polishing tool including a plurality of polishing pads each of which is adapted to turn on a vertical axis and as the tool rotates be brought to the edges of the strip of glass, characterized by supports for the pads including arms each pivoted at one end with vertical axis on the tool and giving support to at least one polishing pad at the other end, whereby any arm may be turned in an appropriate position of the tool to bring a pad supported thereby to an inoperative position in which at least the greater portion of its surface is beyond an edge of the glass whilst the other pads of the tool remain in their operative position supporting the glass, and by means for locking the arms against being so turned whilst the tool is turning. I

The apparatus according to the invention may comprise, on a frame adapted to turn on a vertical axis, a support for each pad characterized by an arm carrying the pad at one end while the other end is pivotally mounted with vertical axis on the frame whereby the arm may be turned, in an appropriate position of the frame, to bring a pad mounted thereon to an inoperative position in which at least the greater. portion of its surface is beyond an edge of the glass, while other pads mounted on the frame remain in their operative position supporting the glass, and by means for locking each arm when the pad there on is in operative position. i

If the mounting of each pad is such that the greater portion only of the pad is moved beyond an edge of the glass, then scraping and cleaning can be readily effected without altering the adjustment of the pad, whilst if the mounting is such that the whole of a pad is moved beyond the edge of the glass, then in addition to facility for scraping and cleaning, the felt can be readily replaced whilst the rest of the pads of the respective polishing tool continue to support the travelling sheet of glass.

When pads are carried on a plurality of subframes each supported on the main frame, the support of each sub-frame on the main frame in accordance with the invention may include an arm carrying the sub-frame at one end whilst the other end is pivotally mounted withvertical axis on the main frame, whereby each arm may be turned, in an appropriateposition of the respective sub-frame, to bring a pad on the sub- 53' frame to an inoperative position in which at least the greater portion of its surface is beyond an edge of the glass, while the other pads mounted on the sub-frame remain in their operative position supporting the glass, and by means for locking each arm when the sub-frame is disposed with all its pads in operative position.

Means are provided for adjusting the height of each individual pad so disposed'that the height adjustment of a pad may be the same before and after the operation of swinging the pad beyond the edge of the glass and returning it to operative position.

In the accompanying diagrammatic drawings is shown by way of example several embodiments of the invention as applied to apparatus for polishing glass including co-axial polishing tools operating simultaneously on both surfaces of the glass.

In the drawings: I

Figure 1 is a View from below of a lower polishing tool, partly broken away, with one pad in non-operative position to give access to the operative surface for renewal or scraping the pad the two other pads remaining in operative position giving support to the strip of glass;

Figure 2 is a part vertical section through the tool illustrated in Figure 1 showing mounting of a pad, and its support, the pad being disposed in operative position;

Figures 3, 4, and 5 show a modification of the arrangement shown in Figure 2!, wherein Figure 3 is a part sectional elevation similar to Figure 2,

Figure 4 is a part sectionalelevation taken the line IV-IV of Figure 5, and

Figure is a sectional plan in two planes indicated by the line V-V in Figure 4.

Figure 6 is a view similar to Figure 2 showing another alternative form of the invention, and

Figure '7 is a view similar to that of Figure 1, but on a reduced scale of an alternative form of polishingtool constructed according to the invention.

Referring first to Figures 1 and 2, l is the travelling, strip of glass which is driven slowly by, driving rollers (not shown) in known manner between co-axial polishing tools of which one only of the lower tools is shown, in a direction parallel to its edge 2 in Figure 1 and in a plane to Which the axes of the tools are normal. The driving shaft 3 of the polishing tool carries a main frame with three arms 4, of which only one is shown. Each arm 4 carries a pivot 5 on which a sub-frame with three arms 6 is mounted to turn freely.

Each sub-frame arm 6 carries a swingable arm 1, mounted, as hereafter explained, to turn in it ona vertical axis, the pivotal end of the arm 1 comprising a sleeve member 8 which is received in a cup-shaped end 9 to the arm 6.

A polishing pad H) with pivot H is mounted to turn freely in the free end of each arm 1. Each polishing pad I0 is covered witha layer of felt l2 secured by a clamp ring [2a in which felt the rouge becomes embeddedand which is supplied with water either to the surface of the glass or to the portion of the pad which protrudes beyond the edge of the glass. Accordingly each pad I 8 is supported on theframe 6' by an arm I which at the free end carries the pad and at the other end is pivotally mounted in the frame arm}.

As the arms 4 of the main frame are rotated by the driving shaft 3, the sub-frames rotate about the pivots 5, in consequence of variations in friction between pads and glass and also each pad rotates about its pivot II. The driving shaft and pivots 5 are vertical, and the pivots ll of the pads are vertical, though they may be set at a very small angle to the vertical and such slight inclination from the vertical of the pivot l I is comprised within the term vertical. Each pad, in the course of the rotations of the main and sub-frames, passes beyond each edge of the glass strip, by coming to the position at an edge 2 of the glass, as shown in Figure 2 and indicated by-the chain line circle Illa in Figure 1, and to the corresponding position at the other edge of the strip. The arm 1 of each pad is normally locked in the position shown in Figure 2 by a screw element 13 entering a slot [4 in the sleeve 8,

When it is desired to obtain access to the surface of any one polishing pad in order to change the felt covering or to clean it by scraping, the rotation of the respective main frame is stopped so that the respective sub-frame is disposed to enable the pad in question to be swung out to the inoperative position. To this end the respective arm I is unlocked by withdrawing the screw element l3 from the slot l4, and the freed arm I is swung through about degrees so that the pad, hown in section in Figure 2, occupies the position of the pad shown wholly beyond the edge 2 of the glass in Figure 1. In this position the felt on the pad can be replaced, or the whole surface of the pad is accessible for scraping. At the same time all the other pads remain in their operative positions, in which they support the glass, and the operation of replacing or cleaning a pad may therefore be carried out without risk of the glas bending and then breaking from lack of support.

Each pad I!) is made individually adjustable in height, as follows: The sleeve 8 is capable of sliding vertically, as well as turning, in the cup 9 of the arm 6, and is supported in the desired vertical position by the pin I5 on which the bottom end iii of the sleeve member 8 rests as clearly shown in Figure 2. The pin l5 has its lower end crew-threaded where it passes through the bottom of the arm 5 at IT, and it is provided with a squared end l8 by which the vertical adjustment of the pad is achieved.

Thus, by turning thesquared ends I8 on the arms 1, the height of the respective pads may be adjusted and thereby the operativesurfaces of all the pads on the tool may be brought into one plane.

It is to be noted that, when a pad is swung outwardly it moves about the pin IS without disturbing the. adjustment for the height of the pad and, similarly, when it is turned back into the operative position it retainsits original vertical adjustment. To avoid risk of turning the pin l5 through friction, a ball thrust bearing (not shown) may be inserted between the end l6 of the sleeve member 8 and the pin l5.

In the alternative construction shown in Figures 3, 4 and 5, the cup Bis formed in two parts, the wall of the cup being formed by boring through the arm 6 and the bottomof the cup being constituted by a cover plate l9, bolted as indicated at lSa to the underside of the hollow extremity of the arm 6, and instead of the threaded portion ll of the pin l5 directly engaging the arm 6, as described with reference to Figure 2, the threaded portion 11 engages in a threaded sleeve 28 formed with feathers Zlwhich cooperate with grooves 22in the sleeve 8 to prevent relative rotation between the sleeve 20 and the sleeve 8.

The vertical adjustment of the threaded pin I to regulate the hei ht of the pad may be effected by means of a bevel gear 23 keyed at 26 on the pin i5 near the top, and an engaging gear 25 fixed on an actuating shaft 26 passing radially through the sleeve 8 of the arm 1. With this arrangement the friction at the screw threaded end I! of the pin it due to the weight of the parts supported thereon, is so much greater than the resistance to turning of the actuating shaft that when the arm i is swung about the pin I5 the latter remains stationary, the gear on the actuating shaft running around the bevel on the pin l 5.

A journal'ball bearing 32 designed to take end thrust, is interposed between the pin l5 and the sleeve 8 and the employment of an anti-friction bearing avoids unintentional displacement of the arm in a vertical direction.

In such an arrangement the adjusting mechanism is completely enclosed and on removing the cover plate [9a the threaded sleeve Ell can also be withdrawn and if necessary replaced by a new threaded sleeve.

A shoulder 33 on the pin i5 and a nut 34 on the lower end of the pin in co-operation with the cover plate l9 and the upper end of the grooves 26 limit the vertical movement of the sleeve 8.

In this construction each arm I is locked in the operative position, shown in Figure 3, to its respective arm 6 by a half round bolt 21 operable by a handle 28 to rotate it within a housing 29 formed on the wall of the cup 9, as most clearly shown in Figure 5. The half round bolt 21 in the locking position straddles a vertical rib 3%] formed on the sleeve 8.

To prevent the bolt inadvertently moving from either the locked or unlocked position, the body of the bolt is formed with flats indicated at 3|, against which a spring (not shown) and housed in the body 29, is adjustably pressed, as will be understood in the art.

As already described with reference to Figure 2, the arm I can be swung on its axis 15 relatively to the arm 6 so that the pad of the arm I so swung is available beyond the edge 2 of the glass for repair or cleaning.

Moreover, if the bevel gear actuating shaft 25 be locked against rotation, e. g., by a rotatable key, (not shown) mounted on the arm 7 similarly to the key 31 hereafter referred to in reference to Figure 6, then swinging the arm I, to give access to the pad surface, will alter the height of the pad, and this action may be used to withdraw the pad slightly from the glass, and on turning the arm back to operating position, the pad will return to its original position of adjustment.

Figure 6 shows an alternative application of the invention, in which a group of pads can be moved together so as to bring any one of the pads of the group to a position in which the whole of its surface is made accessible by bringing it beyond the edge of the glass.

In this arrangement the sub-frame with three arms 6, each carrying a pad in, is adapted to turn on a vertical pivot 5 fixed to an arm 35 having a vertical pivot 36 adapted to turn in the cupped end of the arm 4 of the main frame. The arm 35 is normally locked in the position shown,- by a key 31 engaging a groove 38 in the pivot 35. On turning the key 37 through 180 degrees, a cutaway portion 39 frees the pivot 36 and permits it to turn through 180 degrees to bring the subframe with arms t to a larger radius from the driving shaft 3, and in this position any one of the pads l0 may be brought beyond the edge of the glass to give access to its surface. Accordingly each sub-frame is supported on the mainframe by an arm 35 which at the free end carries the sub-frame and at the other end is pivoted in the main frame.

Each pad N3 has an adjusting device to regulate its height, consisting of a sleeve 8 on which the pad rests, and is adapted to slide in the cup shaped end 9 of the arm 6, the sleeve being supported in any desired position of vertical adjustment by the screw-threaded member 40. In this form also, the movement of the pad for access to its surface and return to operative position does not affect the vertical adjustment of the individual pad. Thrust bearings may, as will be well understood, be interposed between the pad and the sleeve 3 and/or between a collar 4| on the member 40 and the sleeve 8.

The tool illustrated in Figures 1 and 2 or in Figures 3-5 may be modified by reducing'the length of the arm 1 and correspondingly decreas ing the arm 6, whereby the centre of each pad, when in operative position remains unaltered with regard to the edge 2 of the glass, but the swung out position is modified in that the inner part of the pad remains under the edge of the glass for a distance somewhat equivalent to the distance a pad overlies the edge when in operative position. Accordingly the greater part of the pad surface is accessible for scraping or cleaning and the whole is progressively readily accessible for such operation by rotating the pad in the inoperative position and if the felt has to be replaced the pivot i 5 can be lowered, as in any case the pivot would have to be readjusted by lowering to accommodate the new (and thicker) felt.

Similarly the operation of the construction shown in Figure 3 can be modified by reducing the length of the arms 6 and 35 and then by vertically withdrawing a pad slightly from the glass on operating the height adjusting means 25 for the pad, the felt covering may be changed whilst scraping or cleaning can be readily effected.

In Figure '7 a form of polisher is shown having a main frame only, the frame havin four arms 5 and a single pad 10 on each arm. Each pad is mounted on an arm 1 adapted to turn in the cupped end of its arm 4, in the same manner as the arm 1 turns in frame arm 6 illustrated in Figures 2 or 3-5. In this arrangement the arms 1 and 4 are of such length that only the greater part of the pad surface is exposed when in the swung-out position. The right hand pad in Figure 7 is shown moved out to the inoperative position in which there is sufficient access to its surface for scraping and cleaning and by rotation of the pad on its axis the whole surface can be treated.

The form of tool shown in Figure '7 may, of course, be provided with arms 4 and 1 of increased lengths in order that the Whole surface of each pad may be swung beyond the edge 2 of the glass.

By the present invention each pad of polishing apparatus of the kind referred to is capable of being disposed in operative position when the apparatus is turning and of being swung into the inoperative position in which the pad is wholly exposed beyond an edge of a glass strip on which the apparatus is operating, or the major part is exposed so that by rotating the pad in inoperative 7 position the whole surface is progressively exposed.

We claim:

1. Apparatus for polishing the under surface of a horizontal travelling strip of glass comprising a rotatable polishing tool including a plurality of polishing pads each of which is adapted to turn one vertical axis and as the tool rotates be brought to the edges of the strip of glass characterized by supports for the pads including arms each pivoted at one end with vertical axis on the tool and giving support to at least one polishing pad at the other end whereby any arm may be turned in an appropriate position of the tool to bring a pad supported thereby to an inoperative'position in which at least the greater portion of its surface is beyond an edge of the glass whilst the other pads of the tool remain in their operative position supporting the glass, and by means for locking the arms against being so turned whilst,the tool is turning.

2. Apparatus for polishing the under surface of a horizontal travelling strip of glass comprising a polishing tool in which a plurality of polishing pads, each adapted to turn on a vertical axis is supported on a frame adapted to turn on a vertical axis so as to bring each pad on the frame to an edge of the strip of glass, characterized by the support for each pad on the frame including an arm carrying the pad at one end While the other end is pivotally mounted with vertical axis, on the frame, whereby the arm may be turned, in an appropriate position of the frame, to bring a pad mounted thereon to an inoperative position in which at least the greater portion of its surface is beyond an edge of the glass, while other pads mounted on the frame remain in their operative position supporting the glass, and by means for lockingeach arm when the pad thereon is in operative position.

3. Apparatus for polishing the under surface of a horizontal travelling strip of glass comprising a polishing tool in which a plurality of polishing pads each adapted to turn on a vertical axis, is

supported on a plurality of sub-frames, each subframe being supported on a main frame, the main and sub-frames being adapted to turn on vertical axes so as to bring each pad to an edge of the glass, characterized by the support for each sub-frame on the main frame including an arm carrying the sub-frame at one end whilst the other end is pivotally mounted, with vertical axis, on the main frame, whereby each arm may be turned, in an appropriate position of the respective sub-frame, to bring a pad mounted on the sub-frame to an inoperative position in which at least the greater portion of its surface is beyond an edge of the glass, while the other pads mounted on the sub-frame remain in their operative position supporting the glass, and by means for locking each arm when the sub-frame is disposed with all its pads in operative position.

4. Apparatus according to claim 2 characterized by each arm comprising a sleeve at the pivotal end and by the frame being formed with a cup for each sleeve each arm being located on the frame by its sleeve being slidably received by a cup, and each arm being carried in a vertically adjustable pivot mounted on the frame and c0- axially with the cup whereby the arm can be moved relatively to the frame in a vertical direction and by locking means mounted on each cup and operable to engage the respective sleeve and hold that sleeve against angular movement within its cup when the frame is turning.

5. Apparatus according to claim 3 characterized by each pad being carried on its sub-frame by a sleeve slidable axially in a cup formed in the sub-frame, the sleeve being adapted to receive a pivot pin of the respective pad and an axially adjustable member supporting each sleeve within its cup and carried by the frame coaxially with the cup whereby on adjusting the sleeve supporting member the pad carried on the sleeve is displaced axially.

FREDERIC BARNES WALDRON. JANIES HARRIS GRIFFIN. 

